John Calvin Commentary 1 Timothy 6:3

"If any man teacheth a different doctrine, and consenteth not to sound words, [even] the words of our Lord Jesus Christ, and to the doctrine which is according to godliness;" — 1 Timothy 6:3 (ASV)

If anyone teacheth differently—the word ἑτεροδιδασκαλεῖ, being a compound, may also be appropriately translated, teacheth other things. Yet there is no ambiguity about the meaning, for he condemns all those who do not agree with this way of teaching, even if they do not openly and explicitly oppose sound doctrine.

It is possible that someone who does not profess any wicked or open error may still, by trying to insinuate himself through silly babbling, corrupt the doctrine of godliness. For when there is no progress and no edification in the doctrine itself, there is already a departure from Christ's ordinance.

Now, although Paul is not speaking of the explicit supporters of wicked doctrines, but of vain and ungodly teachers who, through their ambition or greed, distort the plain and simple doctrine of godliness, we still see with what sharpness and severity he attacks them. We should not be surprised by this, for it is almost impossible to measure the harm done by preaching that is hypocritical and entirely designed for show and empty display. But who these people are whom he blames becomes clearer from what follows in the next passage.

And consenteth not to sound words—this clause is intended to explain the previous one. It often happens that such people as are described here, carried away by foolish curiosity, despise everything useful and solid, and so indulge in erratic behavior, like unruly horses. And what is this but to reject the sound words of Christ? For they are called 'sound' or 'healthful' because they give us health, or are suited to promote it.

And to the doctrine which is according to godliness—this has the same meaning as the previous clause. For the 'doctrine' will not be consistent with 'godliness' if it does not instruct us in the fear and worship of God, if it does not edify our faith, if it does not train us in patience, humility, and all the duties of love that we owe to our fellow human beings. Therefore, whoever does not strive to teach usefully does not teach as he should; and not only that, but any doctrine that does not lead to the benefit of the hearers is neither godly nor sound, no matter how brilliant its presentation.